Guidewire structure

ABSTRACT

A first guidewire structure includes a medical guidewire extendable beyond a distal end of a medical instrument and having first and second segments, wherein the bending moment of inertia of the first segment is less than the bending moment of inertia of the second segment. A second guidewire structure includes a medical guidewire extendable beyond a distal end of a medical instrument having a mechanized guidewire drive assembly. The medical guidewire has an exterior surface including a repetitive series of spaced-apart surface elevation features. One example of surface elevation features is external threads. The spaced-apart surface elevation features are adapted for operable engagement with the mechanized guidewire drive assembly.

CROSS REFERENCE TO RELATED PATENT APPLICATIONS

This patent application claims priority of U.S. Provisional ApplicationSer. No. 60/571,026 filed May 14, 2004 and U.S. Provisional ApplicationSer. No. 60/571,118 filed May 14, 2004, the entire disclosures of whichare incorporated herein by reference.

This patent application incorporates by reference: US Patent ApplicationPublication 2004/0111019 published Jun. 10, 2004; US Patent ApplicationPublication 2004/0111020 published Jun. 10, 2004; US Patent ApplicationPublication 2004/0199087 published Oct. 7, 2004; US Patent ApplicationPublication 2004/0199088 published Oct. 7, 2004; and US PatentApplication Publication 2004/0230096 published Nov. 18, 2004.

FIELD OF THE INVENTION

The present invention is related generally to guidewire structures, andmore particularly to a medical guidewire.

BACKGROUND OF THE INVENTION

A physician typically accesses and visualizes tissue within a patient'sgastrointestinal (GI) tract with a long, flexible endoscope. For theupper GI, a physician may insert a gastroscope into the sedatedpatient's mouth to examine and treat tissue in the esophagus, stomach,and proximal duodenum. For the lower GI, a physician may insert acolonoscope through the sedated patient's anus to examine the rectum andcolon. Some endoscopes have a working channel, typically about 2.5-3.5millimeters in diameter, extending from a port in the handpiece to thedistal portion of the flexible insertion tube. A physician may insertmedical devices into the working channel to help diagnose or treattissues within the patient. Physicians commonly take tissue biopsiesfrom the mucosal lining of the GI tract using a flexible, biopsy forcepsthrough the working channel of the endoscope.

Insertion of a flexible endoscope, especially into the colon, can be avery time-consuming and uncomfortable procedure for the patient, evenwhen the patient is sedated with drugs. A physician often needs severalminutes to push a flexible endoscope through the convoluted sigmoid, andthe descending, transverse, and ascending portions of the colon. Thephysician may diagnose and/or treat tissues within the colon eitherduring insertion or removal of the endoscope. The flexible endoscope may“loop” within the colon, such as at the sigmoid colon or at the splenicflexure of the colon, so that it becomes difficult to further advancethe endoscope along the colon. When a loop is formed, the force exertedto push the scope stretches the mesentery and causes pain for thepatient. Depending on the anatomy of the patient and the skill of thephysician in manipulating the flexible endoscope, some portions of thecolon may be unexamined, thus increasing the risk of undiagnoseddisease.

Guidewires have been used to aid the introduction of catheters and otherinstruments into many sites in the human body. Many medical applicationsand specific designs of guidewires have been for cardiovascular use.There are, however, specific challenges relating to the use ofguidewires in the GI tract, as opposed to the vascular system. Thus, thebowel is more tortuous, softer and generally of larger diameter.Furthermore, in the case of the small intestine and the colon, these arelonger than most arteries or veins.

Still, scientists and engineers continue to seek improved medicalguidewires.

SUMMARY

A first embodiment of a guidewire structure of the invention includes amedical guidewire. The medical guidewire includes a working portionwhich is extendable as a loop track beyond a distal end of a medicalinstrument. The working portion has a maximum loop-track length andincludes first and second segments together having a length greater thanninety percent of the maximum loop-track length. The first segment has afirst bending moment of inertia and the second segment has a secondbending moment of inertia. The first bending moment of inertia is lessthan the second bending moment of inertia.

A second embodiment of a guidewire structure of the invention includes amedical guidewire. The medical guidewire includes a working portionwhich is extendable as a loop track beyond a distal end of a medicalinstrument having a mechanized guidewire drive assembly. The workingportion includes an exterior surface having a repetitive series ofspaced-apart surface elevation features adapted for operable engagementwith the mechanized guidewire drive assembly.

An alternate first embodiment of a guidewire structure of the inventionincludes a medical guidewire. The medical guidewire is extendable beyonda distal end of a medical instrument. The medical guidewire includesfirst and second segments, wherein the first segment has a first bendingmoment of inertia and the second segment has a second bending moment ofinertia, and wherein the first bending moment of inertia is less thanthe second bending moment of inertia. The first segment has a free endwhich extends beyond the distal end of the medical instrument when themedical guidewire is fully extended.

An alternate second embodiment of a guidewire structure of the inventionincludes a medical guidewire. The medical guidewire is extendable beyonda distal end of a medical instrument having a mechanized guidewire driveassembly. The medical guidewire includes an exterior surface having arepetitive series of spaced-apart surface elevation features adapted foroperable engagement with the mechanized guidewire drive assembly. Themedical guidewire has a free end which extends beyond the distal end ofthe medical instrument when the medical guidewire is fully extended.

Several benefits and advantages are obtained from one or more of theembodiments of the invention. In one application, having a loop-track ornon-loop-track guidewire including a first segment having a bendingmoment of inertia less than that of a second segment allows easierextension of the first segment in a body lumen of a patient followed byeasier extension and temporary anchoring of the second segment andeasier advancement of the medical instrument, as can be appreciated bythe artisan. In the same or a different application, having a loop-trackor non-loop-track guidewire including an exterior surface having arepetitive series of spaced-apart surface elevation features, such asexternal threads, allows operable engagement thereof with a mechanizedguidewire drive assembly for improved guidewire extension and medicalinstrument advancement, as can be appreciated by those skilled in theart. In one employment which utilizes a mechanized guidewire driveassembly, when the surface-elevation-feature engaging component of themechanized guidewire drive assembly is located proximate the distal endof the catheter (insertion tube) of a flexible endoscope, there is lesstendency for the catheter to “loop” within the colon and cause pain tothe patient during a colonoscopy.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a side elevational view of a portion of a first embodiment ofa guidewire structure of the invention including a lubricious sleeveshown in cross section;

FIG. 2 is a schematic side-elevational cutaway view of the guidewirestructure of FIG. 1, with the sleeve omitted for clarity, employed in afirst embodiment of a medical instrument having a catheter;

FIG. 3 is a side elevational view of a portion of a second embodiment ofa guidewire structure of the invention including external threads andincluding a lubricious sleeve shown in cross section;

FIG. 4 is a schematic side-elevational cutaway view of the guidewirestructure of FIG. 3, with the sleeve omitted for clarity, employed in asecond embodiment of a medical instrument having a catheter;

FIG. 5 is a schematic view of a distal end portion of the assemblage ofFIG. 4 in the form of an insertion tube of a colonoscope and employedduring a colonoscopy;

FIG. 6 is a schematic side-elevational cutaway view of a portion of analternate first embodiment of a guidewire structure, with the sleeveomitted for clarity, employed in an alternate first embodiment of amedical instrument having a catheter;

FIG. 7 is a schematic side-elevational cutaway view of an alternatesecond embodiment of a guidewire structure, with the sleeve omitted forclarity, employed in an alternate second embodiment of a medicalinstrument having a catheter;

FIG. 8 is a more detailed view of a distal portion of the catheter ofFIG. 4 showing a particular embodiment of the mechanized guidewire driveassembly including a motor, a spur gear, and a nut gear;

FIG. 9 is an exterior side-elevational view of the nut gear of FIG. 8;

FIG. 10 is an exterior front-elevational view of the nut gear of FIG. 9;

FIG. 11 is a cross-sectional view of the nut gear taken along lines11-11 of FIG. 10;

FIG. 12 is a schematic view of another particular embodiment of themechanized guidewire drive assembly of FIG. 4;

FIG. 13 is a schematic view of a particular embodiment of the mechanizedguidewire drive assembly of FIG. 7;

FIG. 14 is a schematic side-elevational cutaway view of a portion of athird embodiment of a medical instrument of the invention including acatheter and a medical guidewire;

FIG. 15 is a front elevational view of the catheter of the medicalinstrument of FIG. 14 with the medical guidewire removed to show twoguidewire passageway openings;

FIG. 16 is a schematic view of a particular embodiment of the mechanizedguidewire drive assembly of FIG. 14 showing a wire length counter and aforce/torque limiting clutch;

FIG. 17 is a schematic side-elevational cutaway view of a fourthembodiment of a medical instrument of the invention including anarticulated catheter and a medical guidewire;

FIG. 18 is a schematic view of a particular embodiment of the mechanizedguidewire drive assembly of FIG. 17 including a motor and a gearbox,wherein it is noted that the motor is disposed in the catheter;

FIG. 19 is a schematic side-elevational cutaway view of a fifthembodiment of a medical instrument of the invention including anarticulated catheter and a medical guidewire, wherein the motor of themechanized guidewire drive assembly of the medical instrument isdisposed in the handle of the medical instrument, and wherein theportion of the second segment (including the external threads thereof)of the medical guidewire extending proximal of the gearbox has beenomitted for clarity;

FIG. 20 is a schematic side-elevational cutaway view of a sixthembodiment of a medical instrument of the invention including anarticulated catheter and a medical guidewire, wherein the motor of themechanized guidewire drive assembly of the medical instrument isdisposed outside the handle and the catheter of the medical instrument,and wherein the portion of the second segment (including the externalthreads thereof) of the medical guidewire extending proximal of thegearbox has been omitted for clarity;

FIG. 21 is a schematic side-elevational cutaway view of a seventhembodiment of a medical instrument of the invention including aloop-track guidewire and an add-to catheter having a rail;

FIG. 22 is a perspective view of the catheter of FIG. 21 showing thenotches in the rail of the catheter and with the guidewire and theguidewire passageway opening(s) omitted for clarity;

FIG. 23 is a more-detailed top planar view of the rail of FIG. 22,wherein the rail has been laid open to show the transverse extent of thenotches;

FIG. 24 is a distal end view of the catheter of FIG. 22 together with anembodiment of an adjunct medical device having a working channelcontaining a medical device in the form of a cutting blade;

FIG. 25 is a distal end view of the catheter of FIG. 22 together with anembodiment of an adjunct medical device in the form of a connector,wherein the connector is coupled to, and slides along, the rail andwherein the connector is itself adapted to slidably receive arail-coupling portion of a second medical instrument in the form of theadjunct medical device of FIG. 24;

FIG. 26 is a schematic side-elevational cutaway view of an eighthembodiment of a medical instrument of the invention including anon-loop-track guidewire and an add-to catheter having a rail;

FIG. 27 is a distal end view of the catheter of FIG. 26, with theguidewire and the guidewire passageway opening(s) omitted for clarity,together with an embodiment of an adjunct medical device.

DETAILED DESCRIPTION

Before explaining the several embodiments of the present invention indetail, it should be noted that each embodiment is not limited in itsapplication or use to the details of construction and arrangement ofparts and steps illustrated in the accompanying drawings anddescription. The illustrative embodiments of the invention may beimplemented or incorporated in other embodiments, variations andmodifications, and may be practiced or carried out in various ways.Furthermore, unless otherwise indicated, the terms and expressionsemployed herein have been chosen for the purpose of describing theillustrative embodiments of the present invention for the convenience ofthe reader and are not for the purpose of limiting the invention.

It is further understood that any one or more of the following-describedexpressions, embodiments, examples, etc. can be combined with any one ormore of the other following-described expressions, embodiments,examples, etc.

Guidewire Structure

A first aspect of the invention is directed to a guidewire structure. Afirst embodiment of a guidewire structure 10 of the invention is shownin FIGS. 1-2 and includes a medical guidewire 12. The medical guidewire12 includes a working portion 14 which is extendable as a loop trackbeyond a distal end 16 of a medical instrument 18. The working portion14 has a maximum loop-track length and includes first and secondsegments 20 and 22 together having a length greater than ninety percentof the maximum loop-track length. The first segment 20 has a firstbending moment of inertia and the second segment 22 has a second bendingmoment of inertia. The first bending moment of inertia is less than thesecond bending moment of inertia. It is noted that describing the firstbending moment of inertia as less than the second bending moment ofinertia is equivalent to describing the first segment 20 as being moreflexible than the second segment 22.

It is noted that the term “segments” means non-overlapping segments. Itis also noted that the length of the loop track is the distance alongthe loop track from where the first segment 20 begins to extend beyondthe distal end 16 of the medical instrument 18 to where the secondsegment 22 begins to extend beyond the distal end 16 of the medicalinstrument 18. It is further noted that when the working portion 14 isnot fully extended as a loop track beyond the distal end 16 of themedical instrument 18, the length of the loop track extending beyond thedistal end 16 of the medical instrument 18 is less than the maximumloop-track length.

The medical guidewire 12 is adapted to guide the medical instrument 18.In one variation, the medical guidewire 12 is adapted to guide aflexible catheter (also known as a flexible insertion tube) 24 of themedical instrument 18. In one modification, the first and/or secondsegments 20 and/or 22 are disposed to extend beyond the distal end 16 ofthe catheter 24 from passageways inside the catheter 24. In oneillustration, not shown, the first and second segments 20 and 22 extendfrom the same passageway. In a different modification, not shown, thefirst and/or second segments are disposed to extend beyond the distalend of the catheter from outside the exterior surface of the catheterwith the second or both of the segments engaged by guide ways on theexterior surface of the catheter. Other modifications are left to theartisan. Examples of catheters include, without limitation,cardio-vascular catheters, pulmonary catheters, and insertion tubes ofendoscopes such as insertion tubes of gastroscopes and colonoscopes. Inone enablement of the embodiment of FIGS. 1-2, the working portion 14 isadapted for patient intraluminal contact. Examples of body lumens of apatient include, without limitation, the upper GI (gastrointestinal)tract, the lower GI tract, and blood vessel passageways. Other examplesof medical instruments 18, catheters 24, and/or body lumens are left tothe artisan.

In one construction of the guidewire embodiment of FIGS. 1-2, the firstsegment 20 and the second segment 22 have substantially the samematerial composition, wherein the first segment 20 has asubstantially-constant first diameter, wherein the second segment 22 hasa substantially-constant second diameter, and wherein the first diameteris less than the second diameter. In one variation, the working portion14 includes a third segment 26 extending from the second segment 22 tothe first segment 20. The third segment 26 has a length and has avarying third diameter which is substantially equal to the seconddiameter proximate the second segment 22 and which is substantiallyequal to the first diameter proximate the first segment 20. In onemodification, the varying third diameter of the third segment 26substantially linearly decreases from proximate the second segment 22 toproximate the first segment 20. In a different modification, the thirddiameter of the third segment 26 is less than the first and seconddiameters except proximate the first and second segments 20 and 22.

In one employment of the guidewire embodiment of FIGS. 1-2, the workingportion 14 includes a lubricious sleeve 28 surrounding the first segment20. The sleeve 16 creates a low friction surface for easy passagethrough a body lumen of a (human or non-human) patient. Examples ofmaterials for the sleeve 28 include, without limitation,Polytetrafluoroethylene (PTFE), such as Striped Teflon® PTFE availablefrom Zeus, Inc (Orangeburg, S.C.). In one method, the sleeve 28 isapplied over the first segment 20 through a heat-shrink process wellknown in the art. In one variation, the working portion 14, apart fromthe sleeve 28 (or apart from any sleeve), is monolithic.

In one illustration of the guidewire embodiment of FIGS. 1-2, theworking portion 14, apart from any sleeve, is made of a super-elasticalloy such as nitinol available from Nitinol Devices & Components(Fremont, Calif.) and has a suitable diameter for insertion into a bodylumen of a patient. In one example, the first segment 20 has a length ofover 1 meter and a diameter of substantially 0.46 millimeter, the secondsegment 22 has a length of over 1 meter and a diameter of substantially0.76 millimeter, the third segment 26 has a length of substantially 0.08meter, and the sleeve 28 has a wall thickness of substantially 0.11millimeter. Other dimensional choices are left to the artisan.

One technique for using the guidewire structure 10 of the guidewireembodiment of FIGS. 1-2 includes inserting the first segment 20 into afirst guidewire passageway of the catheter 24 from the distal end 16 andinserting the second segment 22 into a second guidewire passageway ofthe catheter 24 from the distal end 16. Then, with the working portion14 extended a minimum distance beyond the distal end 16 of the catheter24, the catheter 24 is manually inserted an initial distance into a bodylumen of a patient. Then, a first guidewire leg 12′ leading to the firstsegment 20 is manually pushed from outside the patient to extend atleast some of the first segment 20 beyond the distal end 16 of thecatheter 24. Then, a second guidewire leg 12″ leading to the secondsegment 22 is pushed from outside the patient to extend at least some ofthe second segment 22 beyond the distal end 16 of the catheter 24 and totemporarily anchor the second segment 22 against the wall of the bodylumen. Then, the first segment 20 is immobilized with respect to thecatheter 24 (by the clinician or by the use of a surgical clamp, springclamp, or collet) and the catheter 24 is manually pushed a furtherdistance into the body lumen while manually pulling on the secondguidewire leg 12″ from outside the patient to retract at least some ofthe second segment 22. The last two steps (described in the previous twosentences) are repeated as necessary to fully insert the catheter 24into the body lumen.

In one example, not shown, of the guidewire embodiment of FIGS. 1-2, themedical guidewire includes surface elevation features to improve thetemporary anchoring of the medical guidewire against the wall of thebody lumen. In one variation, the surface elevation features are presenton then second segment and are absent from the first segment. In thesame or a different variation, the surface elevation features areexternal threads.

A second embodiment of a guidewire structure 110 of the invention isshown in FIGS. 3-5. A first expression of the guidewire embodiment ofFIGS. 3-5 is for a guidewire structure 110 including a medical guidewire112. The medical guidewire 112 includes a working portion 114 which isextendable as a loop track beyond a distal end 116 of a medicalinstrument 118 having a mechanized guidewire drive assembly 130. Theworking portion 114 includes an exterior surface 132 having a repetitiveseries of spaced-apart surface elevation features 134 adapted foroperable engagement with the mechanized guidewire drive assembly 130.

In one arrangement of the first expression of the guidewire embodimentof FIGS. 3-5, the working portion 114 includes first and second segments120 and 122, and the surface elevation features 134 are present on thesecond segment 122 and are absent from the first segment 120. In onevariation, the surface elevation features 134 are chosen from the groupconsisting of periodic threads (also called external threads 136),periodic teeth, periodic holes, and periodic grooves. In the same or adifferent arrangement, the working portion 114 has a maximum loop-tracklength, wherein the first and second segments 120 and 122 together havea length greater than ninety percent of the maximum loop-track length,wherein the first segment 120 has a first bending moment of inertia andthe second segment 122 has a second bending moment of inertia, andwherein the first bending moment of inertia is less than the secondbending moment of inertia.

A second expression of the guidewire embodiment of FIGS. 3-5 is for aguidewire structure 110 including a medical guidewire 112. The medicalguidewire 112 includes a working portion 114 which is extendable as aloop track beyond a distal end 116 of a medical instrument 118 having amechanized guidewire drive assembly 130. The working portion 114includes an exterior surface 132 having external threads 136 adapted foroperable engagement with the mechanized guidewire drive assembly 130.

It is noted that the arrangements previously described for the firstexpression of the guidewire embodiment of FIGS. 3-5 are equallyapplicable to the second expression of the guidewire embodiment of FIGS.3-5 with external threads 136 being the surface elevation feature 134.In one enablement of the second expression of the guidewire embodimentof FIGS. 3-5, the working portion 114 is adapted for patientintraluminal contact. In one example, the medical instrument 118 is acolonoscope which includes a flexible insertion tube (also known as aflexible catheter) 124, and the distal end 116 of the medical instrument118 is the distal end of the flexible insertion tube 124 of thecolonoscope. FIG. 5 shows the working portion 114 of the medicalguidewire 112 disposed in the colon 138 of a patient during acolonoscopy. In one variation, not shown in FIGS. 3-5, the insertiontube 124 includes an imager, a light pathway, and at least onemedical-device passageway (i.e., working channel) for inserting amedical device, such as a wire snare to biopsy a polyp during acolonoscopy.

In one employment of the second expression of the guidewire embodimentof FIGS. 3-5, the working portion 114 includes a lubricious sleeve 128surrounding only the first segment 120. In one variation, the workingportion 114, apart from the sleeve 128, consists essentially of anickel-titanium alloy. In one application, the nickel-titanium alloy isnitinol.

In one construction of the second expression of the guidewire embodimentof FIG. 3-5, the first segment 120 and the second segment 122 havesubstantially the same material composition, wherein the first segment120 has a substantially-constant first diameter, wherein the secondsegment 122, without considering the external threads 136, has asubstantially-constant second diameter, and wherein the first diameteris less than the second diameter. In one variation, the working portion114 includes a third segment 126 extending from the second segment 122to the first segment 120, wherein the third segment 126 has a length andhas a varying third diameter which is substantially equal to the seconddiameter proximate the second segment 122 and which is substantiallyequal to the first diameter proximate the first segment 120. In onemodification, the third diameter of the third segment 126 substantiallylinearly decreases from proximate the second segment 122 to proximatethe first segment. In a different modification, the third diameter ofthe third segment 126 is less than the first and second diameters exceptproximate the first and second segments 120 and 122.

A first method for making the guidewire structure 110 of the secondexpression of the guidewire embodiment of FIGS. 3-5 includes steps a)through e). Step a) includes obtaining a monolithic core wire having adiameter. Step b) includes machining the core wire to create a firstsection, a second section, and a transition section extending from thesecond section to the first section, wherein the first and secondsections each have a substantially constant diameter, and wherein thefirst diameter is less than the second diameter. Step c) includesobtaining a helical spring. Step d) includes disposing the helicalspring to surround the second section. Step e) includes metallurgicallyattaching the helical spring to the second section, wherein the firstsection substantially defines the first segment 120 apart from anysleeve 128, and wherein the second section with themetallurgically-attached helical spring substantially defines the secondsegment 122.

In one enablement of the first method, step e) is chosen from the groupconsisting of soldering and laser welding. In the first method, themetallurgically-attached helical spring defines the external threads136. In the same or a different enablement, the helical spring is anitinol helical spring having a diameter of between 0.13 millimeter and0.51 millimeter (and in one construction substantially 0.30 millimeter).In one variation, the external threads 136 have a constant spacing of 40threads per inch, determining a 0.025 inch pitch, for a fine-pitchapplication or have a constant spacing of 10 threads per inch,determining a 0.10 inch pitch, for a coarse-pitch application. Inanother variation, the external threads 136 have a spacing which variesover the length of the second segment 122.

A second method for making the guidewire structure 110 of the secondexpression of the guidewire embodiment of FIGS. 3-5 includes steps a)and b). Step a) includes obtaining a monolithic core wire. Step b)includes machining the core wire to create the first segment 120, apartfrom any sleeve 128, and to create the second segment 122 including theexternal threads 136.

One technique for using the guidewire structure 110 of the secondexpression of the guidewire embodiment of FIGS. 3-5 includes insertingthe first segment 120 into a first guidewire passageway of the catheter124 from the distal end 116 and inserting the second segment 122 into asecond guidewire passageway of the catheter 124 from the distal end 116to engage the mechanized guidewire drive assembly 130. Then, with theworking portion 114 extended a minimum distance beyond the distal end116 of the catheter 124, the catheter 124 is manually inserted aninitial distance into a body lumen of a patient. Then, a first guidewireleg 112′ leading to the first segment 120 is manually pushed fromoutside the patient to extend at least some of the first segment 120beyond the distal end 116 of the catheter 124. Then, the mechanizedguidewire drive assembly 130 is used to push the second segment 122 toextend at least some of the second segment 122 beyond the distal end 116of the catheter 124 and to temporarily anchor the second segment 122against the wall of the body lumen. Then, the catheter 124 is manuallypushed a further distance into the body lumen while the mechanizedguidewire drive assembly 130 is used to pull on the second segment 122to retract at least some of the second segment 122 into the catheter124. The last two steps are repeated as necessary to fully insert thecatheter 124 into the body lumen.

An alternate first embodiment of a guidewire structure 210 is shown inFIG. 6 and includes a medical guidewire 212. The medical guidewire 212is extendable beyond a distal end 216 of a medical instrument 218. Themedical guidewire 212 includes first and second segments 220 and 222,wherein the first segment 220 has a first bending moment of inertia andthe second segment 222 has a second bending moment of inertia, andwherein the first bending moment of inertia is less than the secondbending moment of inertia. The first segment 220 has a free end 221which extends beyond the distal end 216 of the medical instrument 218when the medical guidewire 212 is fully extended. It is noted that suchfee end 221 makes the medical guidewire 212 a non-loop-track medicalguidewire.

In one application of the guidewire structure 210 of FIG. 6, theanchoring generally comes from the first segment 220 folding back andhaving the second segment 222 begin to fold back. In one variation, theportion of the medical guidewire 212 which can extend beyond the distalend 216 of the catheter 224 has a long length. In one example, the firstsegment 220 has a length between 50 millimeters and 1 meter and has adiameter of substantially 0.25 millimeter, the second segment 222 has alength over 1 meter and has a diameter of substantially 0.76 millimeter,and the third segment 226 has a length of substantially 0.08 meter.

One technique for using the guidewire structure 210 of FIG. 6 includesinserting the first guidewire segment 220 into a guidewire passageway ofthe catheter 224 from the proximal end 217. Further advancement of theguidewire structure 210 will result in advancement of the secondguidewire segment 222 into the same guidewire passageway from theproximal end 217. The catheter 224 is manually inserted into a bodylumen of a patient. Then, the second guidewire portion 222 is manuallyadvanced from the proximal end 217 outside the patient to extend thefirst segment 220 and at least a portion of the second segment 222beyond the distal end 216 of the catheter 224 to temporarily anchor thesecond segment 222 against the wall of the body lumen. Then, thecatheter 224 is manually pushed a further distance into the body lumenwhile manually pulling on the second segment 222 from outside thepatient. The last two steps are repeated as necessary to fully insertthe catheter 224 into the body lumen.

An alternate second embodiment of a guidewire structure is shown in FIG.7. A first expression of the guidewire structure 310 of FIG. 7 includesa medical guidewire 312 which is extendable beyond a distal end 316 of amedical instrument 318 having a mechanized guidewire drive assembly 330.The medical guidewire 312 includes an exterior surface 332 having arepetitive series of spaced-apart surface elevation features 334 adaptedfor operable engagement with the mechanized guidewire drive assembly330. The medical guidewire 312 has a free end 321 which extends beyondthe distal end 316 of the medical instrument 318 when the medicalguidewire 312 is fully extended. It is noted that such fee end 321 makesthe medical guidewire 312 a non-loop-track medical guidewire.

A second expression of the guidewire structure 310 of FIG. 7 includes amedical guidewire 312 which is extendable beyond a distal end 316 of amedical instrument 318 having a mechanized guidewire drive assembly 330.The medical guidewire 312 includes an exterior surface 332 havingexternal threads 336 adapted for operable engagement with the mechanizedguidewire drive assembly 330. The medical guidewire 312 has a free end321 which extends beyond the distal end 316 of the medical instrument318 when the medical guidewire 312 is fully extended.

In one application of the second expression of the guidewire structure310 of FIG. 7, the external threads 336 themselves act to anchor themedical guidewire 312 when the external threads 336 are disposed alongthe wall of the body lumen, independent of any medical-guidewire foldback and especially when the external threads 336 extend far into thebody lumen from the distal end 316 of the medical instrument 318. In oneexample, the first segment 320 has a length between 50 millimeters and 1meter and has a diameter of substantially 0.25 millimeter, the secondsegment 322 has a length over 1 meter and has a diameter ofsubstantially 0.76 millimeter, and the third segment 326 has a length ofsubstantially 0.08 meter.

One technique for using the second expression of the guidewire structure310 of FIG. 7 includes inserting the second segment 322 into a guidewirepassageway of catheter 324 from the distal end 316 to engage amechanized guidewire assembly 330. In one variation, the mechanizeddrive assembly 330 is used to draw all of the guidewire structure 310,including second segment 322 and first segment 320, within the catheter324. A second guidewire passageway, if present, of the catheter 324 isleft completely open for other accessories. Then, the mechanizedguidewire assembly 330 is used to push the first segment 320 and aportion of the second segment 322 to extend beyond the distal end 316 ofthe catheter 324 into the body lumen and to temporarily anchor thesecond segment 322 against the wall of the body lumen. Then, thecatheter 324 is manually pushed a further distance into the body lumenwhile the mechanized guidewire drive assembly 330 is used to pull on thesecond segment 322 to retract at least some of second segment 322 intothe catheter 324. The last two steps are repeated as necessary to fullyinsert the catheter 324 into the body lumen.

Medical Instrument Having a Medical Guidewire

A second aspect of the invention is directed to a medical instrumenthaving a medical guidewire. A first embodiment of a medical instrument18 of the invention is shown in FIGS. 1-2 and includes a flexiblecatheter 24 and a medical guidewire 12. The catheter 24 has a distal end16 insertable into a body lumen of a patient. The medical guidewire 12includes a working portion 14 which is extendable as a loop track beyondthe distal end 16 of the catheter 24. The working portion 14 has amaximum loop-track length and includes first and second segments 20 and22 together having a length greater than ninety percent of the maximumloop-track length. The first segment 20 has a first bending moment ofinertia and the second segment 22 has a second bending moment ofinertia. The first bending moment of inertia is less than the secondbending moment of inertia. In one example, the catheter 24 is aninsertion tube of a flexible endoscope (with the endoscope imager,working channel, etc. omitted from FIGS. 1-2 for clarity).

A method for operating the medical instrument 18 of themedical-instrument embodiment of FIGS. 1-2 is now described, wherein themedical guidewire 12 includes a first guidewire leg 12′ having a freeend disposed outside the patient and leading to the first segment 20 andincludes a second guidewire leg 12″ having a free end disposed outsidethe patient and leading to the second segment 22. The method includessteps a) through d). Step a) includes manually inserting the distal end16 of the catheter 24 an initial distance into the body lumen of thepatient. Step b) includes manually pushing the first guidewire leg 12′to extend at least some of the first segment 20 beyond the distal end 16of the catheter 24. Step c) includes manually pushing the secondguidewire leg 12″ to extend at least some of the second segment 22beyond the distal end 16 of the catheter 24 and to temporarily anchorthe second segment 22 against a wall of the body lumen. Step d) includesimmobilizing the first guidewire leg 12′ with respect to the catheter 24and manually pushing the catheter 24 a further distance into the bodylumen while manually pulling on the second guidewire leg 12″ to retractat least some of the second segment 22. In one extension of the method,steps c) and d) are repeated.

A second embodiment of a medical instrument 118 of the invention isshown in FIGS. 3-5 and 8-11. A first expression of themedical-instrument embodiment of FIGS. 3-5 and 8-11 is for a medicalinstrument 118 including a flexible catheter 124, a mechanized guidewiredrive assembly 130, and a medical guidewire 112. The catheter 124 has adistal end 116 insertable into a body lumen of a patient. The medicalguidewire 112 includes a working portion 114 which is extendable as aloop track beyond the distal end 116 of the catheter 124. The workingportion 114 includes an exterior surface 132 having a repetitive seriesof spaced-apart surface elevation features 134 adapted for operableengagement with the mechanized guidewire drive assembly 130.

In one arrangement of the first expression of the medical-instrumentembodiment of FIGS. 3-5 and 8-11, the mechanized guidewire driveassembly 130 includes a surface-elevation-feature engaging component 140disposed within the catheter 124 toward the distal end 116 of thecatheter 124. “Toward the distal end” means closer to the distal endthan to the proximal end. Examples of surface-elevation-feature engagingcomponents include, without limitation, a nut gear 142, a worm gear, aspoke gear, etc. It is noted that the previously-described arrangements,variations, etc. of the first expression of the guidewire embodiment ofFIGS. 3-5 are equally applicable to the first expression of themedical-instrument embodiment of FIGS. 3-5 and 8-11.

A second expression of the medical-instrument embodiment of FIGS. 3-5and 8-11 is for a medical instrument 118 including a flexible catheter124, a mechanized guidewire drive assembly 130, and a medical guidewire112. The catheter 124 has a distal end 116 insertable into a body lumenof a patient. The medical guidewire 112 includes a working portion 114which is extendable as a loop track beyond the distal end 116 of thecatheter 124. The working portion 114 includes an exterior surface 132having external threads 136 adapted for operable engagement with themechanized guidewire drive assembly 130.

In a first construction of the second expression of themedical-instrument embodiment of FIGS. 3-5 and 8-11, the mechanizedguidewire drive assembly 130 includes a motor 144, a spur gear 146, anda nut gear 142. The motor 144 has a rotatable motor shaft 148, and thespur gear 146 is attached to the motor shaft 148. The nut gear 142includes external teeth 150 which are engaged by the spur gear 146. Thenut gear 142 includes internal threads 152 which threadably engage theexternal threads 136 of the medical guidewire 112. The spur gear 146 andthe nut gear 142 are disposed within the catheter 124.

In one variation of the first construction, the motor 144 is disposedwithin the catheter 124. In a different variation, not shown, the motoris disposed outside the proximal end of the catheter, wherein the motorshaft of the motor is a flexible motor shaft. In one modification, notshown, the motor is disposed in the handle of the medical instrument. Inanother modification, not shown, the motor is disposed in a console.Other motor locations are left to the artisan. In one application, themotor 144 is a rotary motor. In a different application, the mechanizedguidewire drive assembly includes a linear motor.

In a second construction (not shown) of the second expression of themedical-instrument embodiment of FIGS. 3-5 and 8-11, the mechanizedguidewire drive assembly 130 does not include a motor but does include anon-motorized mechanism which the clinician uses to extend the medicalguidewire. In one example, the non-motorized mechanism includes a handcrank which has a rotatable flexible output shaft leading to a gearboxoperatively connectable to the medical guidewire. Other examples areleft to the artisan.

In one enablement of the second expression of the medical-instrumentembodiment of FIGS. 3-5 and 8-11, the working portion 114 includes firstand second segments 120 and 122. The external threads 136 are present onthe second segment 122 and are absent from the first segment 120. In onevariation, the working portion 114 has a maximum loop-track length,wherein the first and second segments 120 and 122 together have a lengthgreater than ninety percent of the maximum loop-track length. In thisvariation, the first segment 120 has a first bending moment of inertiaand the second segment 122 has a second bending moment of inertia,wherein the first bending moment of inertia is less than the secondbending moment of inertia. In one modification, the working portion 114includes a third segment 126 extending from the second segment 122 tothe first segment 120, wherein the third segment 126 has a length andhas a varying third diameter. The varying third diameter issubstantially equal to the second diameter proximate the second segment122 and is substantially equal to the first diameter proximate the firstsegment 120. In one example, the internal threads 152 of the nut gear142 are disposed a distance from the distal end 116 of the catheter 124substantially equal to the length of the third segment 126 of theworking portion 114 of the medical guidewire 112.

In one deployment of the second expression of the medical-instrumentembodiment of FIGS. 3-5 and 8-11, the catheter 124 is an insertion tubeof a flexible endoscope (with the endoscope imager, working channel,etc. omitted from FIGS. 3-5 and 8-11 for clarity). In one variation, theworking portion 114 includes a lubricious sleeve 128 surrounding onlythe first segment 120. In one choice of materials, the working portion114, apart from the sleeve 128, consists essentially of anickel-titanium alloy. In one application, the nickel-titanium alloy isnitinol.

This paragraph describes in more detail one configuration of anembodiment of the mechanized guidewire drive assembly 130. As shown inFIG. 8, the first segment 120 of the medical guidewire 112 is seenextending from the first guidewire passageway 154 within the catheter124, and the second segment 122 of the medical guidewire 112 is seenextending from the second guidewire passageway 156 within the catheter124. In this configuration, the catheter 124 includes a more rigidportion 158 (such as an injection molded polycarbonate or other plasticportion having two halves which fit together in a clamshell fashion)which houses the mechanized guidewire drive assembly 130 and which hasstabilizing ribs 160 to constrain the motor 144. The medical instrument118 also includes a lead 162 supplying power to the motor 144. In oneexample, the motor 144 is a miniature DC (direct current) motor such asFaulhaber motor model 0816-006 (available from MicroMo Electronics, Inc.of Clearwater, Fla.) with a gearbox having a reduction ratio of 64:1. Inthis example, the spur gear 146 has 12 teeth, has a pitch diameter of 8millimeters, and is supported on its non-motor side by a gear bearing164. In this example, the nut gear 142 has 6 or 12 external teeth 150and is linearly constrained by a pair of bosses 166. Thus, rotation andcounter-rotation of the motor 144 results in extension and retraction ofthe second segment 122 of the medical guidewire 112. In one application,air is introduced into the body lumen through the first guidewirepassageway 154 during a colonoscopy. In an alternate configuration, notshown, the spur gear is disposed between two universal joints whichtogether are disposed between two smaller motors to provide a tighterbending radius for the catheter, as can be appreciated by those skilledin the art. Other configurations are left to the artisan.

A method for operating the medical instrument 118 of the secondexpression of the medical-instrument embodiment of FIGS. 3-5 and 8-11 isnow described, wherein the medical guidewire 112 includes a firstguidewire leg 112′ having a free end disposed outside the patient andleading to the first segment 120. The method includes steps a) throughd). Step a) includes manually inserting the distal end 116 of thecatheter 124 an initial distance into the body lumen of the patient.Step b) includes manually pushing the first guidewire leg 112′ to extendat least some of the first segment 120 beyond the distal end 116 of thecatheter 124. Step c) includes using the mechanized guidewire driveassembly 130 to extend at least some of the second segment 122 beyondthe distal end 116 of the catheter 124 and to temporarily anchor thesecond segment 122 against a wall of the body lumen. Step d) includesmanually pushing the catheter 124 a further distance into the body lumenwhile using the mechanized guidewire drive assembly 130 to pull on thesecond segment 122 to retract at least some of the second segment 122into the catheter 124. In one extension of the method, steps c) and d)are repeated.

An alternate first embodiment of a medical instrument 218 is shown inFIG. 6 and includes a flexible catheter 224 and a medical guidewire 212.The catheter 224 has a distal end 216 insertable into a body lumen of apatient. The medical guidewire 212 is extendable beyond the distal end216 of the catheter 224. The medical guidewire 212 includes first andsecond segments 220 and 222, wherein the first segment 220 has a firstbending moment of inertia and the second segment 222 has a secondbending moment of inertia, and wherein the first bending moment ofinertia is less than the second bending moment of inertia. The firstsegment 220 has a free end 221 which extends beyond the distal end 216of the catheter 224 when the medical guidewire 212 is fully extended.

An alternate second embodiment of a medical instrument is shown in FIG.7. A first expression of the medical-instrument 318 of FIG. 7 includes aflexible catheter 324, a mechanized guidewire drive assembly 330, and amedical guidewire 312. The catheter 324 has a distal end 316 insertableinto a body lumen of a patient. The medical guidewire 312 is extendablebeyond the distal end 316 of the catheter 324. The medical guidewire 312includes an exterior surface 332 having a repetitive series ofspaced-apart surface elevation features 334 adapted for operableengagement with the mechanized guidewire drive assembly 330. The medicalguidewire 312 has a free end 321 which extends beyond the distal end 316of the catheter 324 when the medical guidewire 312 is fully extended.

A second expression of the medical instrument 318 of FIG. 7 includes aflexible catheter 324, a mechanized guidewire drive assembly 330, and amedical guidewire 312. The catheter 324 has a distal end 316 insertableinto a body lumen of a patient. The medical guidewire 312 is extendablebeyond the distal end 316 of the catheter 324. The medical guidewire 312includes an exterior surface 332 having external threads 336 adapted foroperable engagement with the mechanized guidewire drive assembly 330.The medical guidewire 312 has a free end 321 which extends beyond thedistal end 316 of the catheter 324 when the medical guidewire 312 isfully extended.

Medical Instrument Having a Controlled Guidewire Feed

A third aspect of the invention is directed to a medical instrumenthaving a controlled guidewire feed, a first embodiment of which is shownin FIGS. 3-4 and 12. A first expression of the embodiment of FIGS. 3-4and 12 is for a medical instrument 118 including a flexible catheter124, a medical guidewire 112, and a mechanized guidewire drive assembly130. The catheter 124 has a distal end 116 insertable into a body lumenof a patient. The mechanized guidewire drive assembly 130 is adapted foroperable engagement with the medical guidewire 112 to extend the medicalguidewire 112 beyond the distal end 116 of the catheter 124. Themechanized guidewire drive assembly 130 includes a motor 144 andincludes a controller 168 which drives the motor 144 with a drivingforce, wherein the driving force has a predetermined upper limit.

In the broadest application of the third aspect of the invention, asdescribed in the previous paragraph, the medical guidewire 112 can be aloop-track or a non-loop-track medical guidewire, the medical guidewire112 may have, but does not require, segments having different bendingmoment indices and/or different diameters (or other differentcross-sectional shapes/sizes), and the medical guidewire 112 may have,but does not require, surface elevation features 134 such as externalthreads 136. In one illustration, not shown, a mechanized pinch rollerextends a smooth-exterior-surfaced medical guidewire beyond the distalend of the catheter.

In one deployment of the first expression of the embodiment of FIGS. 3-4and 12, the motor 144 is a rotary motor which produces a torque inresponse to the driving force of the controller 168. In one variation,the motor 144 is a DC (direct current) motor, wherein the driving forceis an electric current, wherein the torque is related to the electriccurrent, wherein the predetermined upper limit is a predeterminedelectric-current upper limit, and wherein the controller 168 includes acurrent limiter 170 which limits the electric current to thepredetermined electric-current upper limit. In one implementation, thepredetermined electric-current upper limit is experimentally establishedfrom at least measurements of the torque of the DC motor and a comfortlevel of at least one patient undergoing at least one medical procedureusing the medical instrument 118 without any predeterminedelectric-current upper limit. Other types of driving forces such as,without limitation, pulse-width-modulation (PWM) and other types ofmotors are left to the artisan. In one example, a lead 169 suppliespower to the controller 168 and a lead 162 supplies power to the motor144 from the controller 168.

In one enablement of the first expression of the embodiment of FIGS. 3-4and 12, the medical guidewire 112 includes a working portion 114 whichis extendable as a loop track beyond the distal end 116 of the catheter124, wherein the working portion 114 has a maximum loop-track length andincludes first and second segments 120 and 122 together having a lengthgreater than ninety percent of the maximum loop-track length. In thisenablement, the first segment 120 has a first bending moment of inertiaand the second segment 122 has a second bending moment of inertia,wherein the first bending moment of inertia is less than the secondbending moment of inertia. In this enablement, the mechanized guidewiredrive assembly 130 is adapted for operable engagement with the secondsegment and not the first segment.

In one construction of the first expression of the embodiment of FIGS.34 and 12, the motor 144 is disposed within substantially fiftycentimeters of the distal end 116 of the catheter 124. In one variation,the catheter 124 is an insertion tube of a flexible endoscope. It isnoted that in one utilization, having the motor 144 disposed toward, andeven proximate, the distal end 116 of the catheter 124 reduces thelength of the motor shaft 148 leading to the gearbox 172 which betterrelates patient discomfort to motor driving force, as can be appreciatedby those skilled in the art. In one modification, the gearbox 172includes the spur gear 146 and nut gear 142 arrangement of theparticular embodiment of the mechanized guidewire drive assembly 130shown in FIG. 8.

A second expression of the embodiment of FIGS. 3-4 and 12 is for amedical instrument 118 including a flexible catheter 124, a medicalguidewire 112, and a mechanized guidewire drive assembly 130. Thecatheter 124 has a distal end 116 insertable into a body lumen of apatient. The medical guidewire 112 includes a working portion 114 whichis extendable as a loop track beyond the distal end 116 of the catheter124, wherein the working portion 114 includes an exterior surface 132having a repetitive series of spaced-apart surface elevation features134. The mechanized guidewire drive assembly 130 is adapted for operableengagement with the surface elevation features 134. The mechanizedguidewire drive assembly 130 includes a motor 144 and includes acontroller 168 which drives the motor 144 with a driving force, whereinthe driving force has a predetermined upper limit.

In one employment of the second expression of the embodiment of FIGS.3-4 and 12, the working portion 114 includes first and second segments120 and 122, wherein the surface elevation features 134 are present onthe second segment 122 and are absent from the first segment 120. It isnoted that the deployments, enablements, constructions, etc. of thepreviously described first expression of the embodiment of FIGS. 3-4 and12 are equally applicable to the second expression of the embodiment ofFIGS. 3-4 and 12.

A third expression of the embodiment of FIGS. 3-4 and 12 is for amedical instrument 118 including a flexible catheter 124, a medicalguidewire 112, and a mechanized guidewire drive assembly 130. Thecatheter 124 has a distal end 116 insertable into a body lumen of apatient. The medical guidewire 112 includes a working portion 114 whichis extendable as a loop track beyond the distal end 116 of the catheter124, wherein the working portion 114 includes an exterior surface 132having external threads 136. The mechanized guidewire drive assembly 130is adapted for operable engagement with the external threads 136. Themechanized guidewire drive assembly 130 includes a motor 144 andincludes a controller 168 which drives the motor 144 with a drivingforce, wherein the driving force has a predetermined upper limit.

In one employment of the third expression of the embodiment of FIGS. 3-4and 12, the working portion 114 includes first and second segments 120and 122, wherein the external threads 136 are present on the secondsegment 122 and are absent from the first segment 120. It is noted thatthe deployments, enablements, constructions, etc. of the previouslydescribed first expression of the embodiment of FIGS. 3-4 and 12 areequally applicable to the third expression of the embodiment of FIGS.3-4 and 12.

A second embodiment of the third aspect of the invention is shown inFIGS. 7 and 13. A first expression of the embodiment of FIGS. 7 and 13is for a medical instrument 318 including a flexible catheter 324, amedical guidewire 312, and a mechanized guidewire drive assembly 330.The catheter 324 has a distal end 316 insertable into a body lumen of apatient. The medical guidewire 312 is extendable beyond the distal end316 of the catheter 324. The medical guidewire 312 includes an exteriorsurface 332 having a repetitive series of spaced-apart surface elevationfeatures 334. The medical guidewire 312 has a free end 321 which extendsbeyond the distal end 316 of the catheter 324 when the medical guidewire312 is fully extended. The mechanized guidewire drive assembly 330 isadapted for operable engagement with the surface elevation features 334.The mechanized guidewire drive assembly 330 includes a motor 344 andincludes a controller 368 which drives the motor 344 with a drivingforce, wherein the driving force has a predetermined upper limit.

A second expression of the embodiment of FIGS. 7 and 13 is for a medicalinstrument 318 including a flexible catheter 324, a medical guidewire312, and a mechanized guidewire drive assembly 330. The catheter 324 hasa distal end 316 insertable into a body lumen of a patient. The medicalguidewire 312 is extendable beyond the distal end 316 of the catheter324. The medical guidewire 312 includes an exterior surface 332 havingexternal threads 336. The medical guidewire 312 has a free end 321 whichextends beyond the distal end 316 of the catheter 324 when the medicalguidewire 312 is fully extended. The mechanized guidewire drive assembly330 is adapted for operable engagement with the external threads 336.The mechanized guidewire drive assembly 330 includes a motor 344 andincludes a controller 368 which drives the motor 344 with a drivingforce, wherein the driving force has a predetermined upper limit.

In one example of the second expression of the embodiment of FIGS. 7 and13, a lead 369 supplies power to the controller 368 and a lead 362supplies power to the motor 344 from the controller 368.

Medical Instrument Having a Catheter and a Medical Guidewire

A fourth aspect of the invention is directed to a medical instrumenthaving a catheter and a medical guidewire, an embodiment of which isshown in FIGS. 14-16. A first expression of the embodiment of FIGS.14-16 is for a medical instrument 418 including a flexible catheter 424and a medical guidewire 412. The catheter 424 has a distal end portion417 which has a substantially bullet-nose shape, which is insertableinto a body lumen of a patient, and which has at least one guidewirepassageway opening 474. The medical guidewire 412 has a working portion414 extendable beyond the at-least-one guidewire passageway opening 474.

A catheter distal end portion 417 having a substantially bullet-noseshape is a catheter distal end portion 417 with a cross section having aperimeter which has a shape of substantially a circle, wherein thecircle continuously decreases in size as one moves toward the distal end416, and wherein the distal end 416, as seen in a side-elevation view,is either rounded or flat. In one variation, the distal end portion 417has a substantially hemispherical shape and the distal end 416 isrounded as seen in FIG. 14. In a different variation, not shown, thedistal end portion has a substantially truncated conical shape and thedistal end is flat. Other variations, including a substantiallyparabolic distal end portion, are left to the artisan.

In the broadest application of the first expression of the embodiment ofFIGS. 14-16, as described in the second previous paragraph, the medicalinstrument 418 many have, but does not require a mechanized guidewiredrive assembly 430, the medical guidewire 412 can be a loop-track or anon-loop-track medical guidewire, the medical guidewire 412 may have,but does not require, segments having different bending moment indicesand/or different diameters (or other different cross-sectionalshapes/sizes), and the medical guidewire 412 may have, but does notrequire, surface elevation features 434 such as external threads 436.

In one implementation of the first expression of the embodiment of FIGS.14-16, the working portion 414 is extendable as a loop track beyond theat-least-one guidewire passageway opening 474. In one variation, theworking portion 414 has a maximum loop-track length and includes firstand second segments 420 and 422, wherein the first and second segments420 and 422 together have a length greater than ninety percent of themaximum loop-track length, wherein the first segment 420 has a firstbending moment of inertia and the second segment 422 has a secondbending moment of inertia, and wherein the first bending moment ofinertia is less than the second bending moment of inertia. In the sameor a different variation, the medical instrument 418 includes amechanized guidewire drive assembly 430, the working portion 414includes first and second segments 420 and 422, the second segment 422includes a repetitive series of spaced-apart surface elevation features434 adapted for operable engagement with the mechanized guidewire driveassembly 430, and the mechanized guidewire drive assembly 430 includes asurface-elevation-feature engaging component 440 disposed within thecatheter 424 toward the distal end 416. In one example, the surfaceelevation features 434 are external threads 436.

A second expression of the embodiment of FIGS. 14-16 is for a medicalinstrument 418 including a flexible catheter 424, a medical guidewire412, and at least one wire length counter 476 and 478. The catheter 424has a distal end 416 which is insertable into a body lumen of a patient.The medical guidewire 412 has a working portion 414 extendable beyondthe distal end 416 of the catheter 424. The at-least-one wire lengthcounter 476 and 478 is operatively connectable to the medical guidewire412 to measure a length of the working portion 414 being extended beyondthe distal end 416 of the catheter 424.

In the broadest application of the second expression of the embodimentof FIGS. 14-16, as described in the previous paragraph, the medicalinstrument 418 many have, but does not require a mechanized guidewiredrive assembly 430, the medical guidewire 412 can be a loop-track or anon-loop-track medical guidewire, the medical guidewire 412 may have,but does not require, segments having different bending moment indicesand/or different diameters (or other different cross-sectionalshapes/sizes), and the medical guidewire 412 may have, but does notrequire, surface elevation features 434 such as external threads 436.

It is noted that a wire length counter 476 and 478 is any device whichmeasures the extension length, from a reference position, of an extendedwire, such devices being well known to those skilled in the art. It isalso noted that the implementations, variations, examples, etc. of thefirst expression of the embodiment of FIGS. 14-16 are equally applicableto the second expression of the embodiment of FIGS. 14-16.

In one application of the second expression of the embodiment of FIGS.14-16, the at-least-one wire length counter 476 and 478 includes a firstwire length counter 476 operatively connectable to the second segment422 to measure a length of the second segment 422 being extended beyondthe distal end 416 of the catheter 424. In one variation, theat-least-one wire length counter 476 and 478 includes a second wirelength counter 478 operatively connectable to the first segment 420 tomeasure a length of the first segment 420 being extended beyond thedistal end 416 of the catheter 424. It is noted that this applicationand/or variation can be used with or without a mechanized guidewiredrive assembly 430, as can be appreciated by the artisan. In onemodification, wherein a mechanized guidewire drive assembly 430 isemployed, the mechanized guidewire drive assembly 430 includes a motor444 having a motor shaft 449, and the first wire length counter 476includes an encoder 480 operatively connected to the motor shaft 449. Inone enablement, not shown, the first and second wire length counters 476and 478 include a display (such as a graphical or numerical display) ona console which is viewable by the clinician. In one extension, notshown, the catheter 424 includes length markings. In one example, a lead462 supplies power to the motor 144.

A third expression of the embodiment of FIGS. 14-16 is for a medicalinstrument 418 including a flexible catheter 424, a medical guidewire412, and a force/torque-limiting clutch 482. The catheter 424 has adistal end 416 insertable into a body lumen of a patient. The medicalguidewire 412 includes a working portion 414 which is extendable beyondthe distal end 416 of the catheter 424. The force/torque-limiting clutch482 is operatively connectable to the medical guidewire 412.

In the broadest application of the third expression of the embodiment ofFIGS. 14-16, as described in the previous paragraph, the medicalinstrument 418 many have, but does not require a mechanized guidewiredrive assembly 430, the medical guidewire 412 can be a loop-track or anon-loop-track medical guidewire, the medical guidewire 412 may have,but does not require, segments having different bending moment indicesand/or different diameters (or other different cross-sectionalshapes/sizes), and the medical guidewire 412 may have, but does notrequire, surface elevation features 434 such as external threads 436. Inone example, not shown, the medical guidewire is manually extended bythe clinician and the force/torque-limiting clutch includes aforce-limiting clutch. In another example, a mechanized guidewire driveassembly 430 is employed and includes a motor 444, wherein the motor 444is a rotary motor, and wherein the force/torque-limiting clutch 482 is atorque-limiting clutch. Other examples are left to the artisan.

In one employment of the third expression of the embodiment of FIGS.14-16, the medical instrument 418 also includes a mechanized guidewiredrive assembly 430, wherein the medical guidewire 412 is adapted foroperable engagement with the mechanized guidewire drive assembly 430,and wherein the mechanized guidewire drive assembly 430 includes theforce/torque-limiting clutch 482. In one variation, theforce/torque-limiting clutch 482 includes a slip clutch 483. In onemodification, the mechanized guidewire drive assembly 430 includes arotatable shaft (such as, but not limited to, a motor shaft 448) and agearbox 472, wherein the gearbox 472 is adapted to operatively engagethe medical guidewire 412, and wherein the slip clutch 483 is disposedbetween, and operatively connected to, the rotatable shaft (such as themotor shaft 448) and the gearbox 472. In one example, the mechanizedguidewire drive assembly 430 includes a motor 444 operatively connectedto the rotatable shaft (such as the motor shaft 448).

In one construction of the third expression of the embodiment of FIGS.14-16, the slip clutch 483 of FIG. 16 includes a coupler (not shown)which is rotated by the flexible (in this construction) rotatable shaft(such as the motor shaft 448) and which includes six finger projections.The six finger projections surround a hexagonal output shaft 481 of theslip clutch 483. The coupler also includes a plurality of O-rings whichsurround, and apply a pressure against, the finger projections. When themoving medical guidewire 412 encounters a threshold resistance, thehexagonal output shaft 481 stops rotating and the rotating fingerprojections slip over the corners of the hexagonal output shaft 481.When the resistance encountered by the medical guidewire 412 falls belowthe threshold resistance, the rotating finger projections stay on theflats of the hexagonal output shaft 481. In this way, this constructionof the slip clutch 483 interrupts the rotation of the hexagonal outputshaft 481 when a threshold resistance is encountered, but allowsrotation when the resistance falls below the threshold value. Otherconstructions of a slip clutch and/or a force/torque-limiting clutch 482are left to the artisan.

Medical Instrument Having a Guidewire and Articulated Catheter

A fifth aspect of the invention is directed to a medical instrumenthaving a guidewire and articulated catheter, a first embodiment of whichis shown in FIGS. 17-18. A first expression of the embodiment of FIGS.17-18 is for a medical instrument 518 including a flexible catheter 524and a medical guidewire 512. The catheter 524 has a distal end 516 andan articulated section 584 insertable into a body lumen of a patient,wherein the articulated section 584 is adapted to be controlled fromoutside the body lumen. The medical guidewire 512 includes a workingportion 514 which is extendable as a loop track beyond the distal end516 of the catheter 524. The working portion 514 has a maximumloop-track length and includes first and second segments 520 and 522together having a length greater than ninety percent of the maximumloop-track length. The first segment 520 has a first bending moment ofinertia and the second segment 522 has a second bending moment ofinertia. The first bending moment of inertia is less than the secondbending moment of inertia.

In the broadest application of the first expression of the embodiment ofFIGS. 17-18, as described in the previous paragraph, the medicalinstrument 518 many have, but does not require a mechanized guidewiredrive assembly 530, and the medical guidewire 512 may have, but does notrequire, surface elevation features 534 such as external threads 536.

In one arrangement of the first expression of the embodiment of FIGS.17-18, the articulated section 584 is disposed toward (and in oneexample proximate) the distal end 516. In one variation, the medicalinstrument 518 includes a handle 586 having a control input device 588,wherein the handle 586 is connected to the catheter 524, and wherein thecontrol input device 588 is operatively connected to the articulatedsection 584. Examples of control input devices include, withoutlimitation, rotatable control knobs, control switches, and controlbuttons. In one modification, the control input device 588 includes acontrol knob 590 and the medical instrument 518 includes two controlcables 592 each having one end connected to a corresponding anchor point594 in the articulated section 584 and each having the other endoperatively connected to the control knob 590, wherein rotation of thecontrol knob 590 bends the articulated section 584 in one direction andcounter-rotation of the control knob 590 bends the articulated section584 in the opposite direction, as can be appreciated by those skilled inthe art. Other mechanisms for bending the articulated section 584 areleft to the artisan. In one application, the catheter 524 is aninsertion tube of a flexible endoscope (with the endoscope imager,working channel, etc. omitted from FIGS. 17-18 for clarity).

A second expression of the embodiment of FIGS. 17-18 is for a medicalinstrument 518 including a flexible catheter 524, a mechanized guidewiredrive assembly 530, and a medical guidewire 512. The catheter 524 has adistal end 516 and an articulated section 584 insertable into a bodylumen of a patient, wherein the articulated section 584 is adapted to becontrolled from outside the body lumen. The medical guidewire 512includes a working portion 514 which is extendable as a loop trackbeyond the distal end 516 of the catheter 524. The working portion 514includes an exterior surface 532 having a repetitive series ofspaced-apart surface elevation features 534 adapted for operableengagement with the mechanized guidewire drive assembly 530.

In one arrangement of the second expression of the embodiment of FIGS.17-18, the articulated section 584 is disposed toward (and in oneexample proximate) the distal end 516. In one variation, the medicalinstrument 518 includes a handle 586 having a control input device 588,wherein the handle 586 is connected to the catheter 524, and wherein thecontrol input device 588 is operatively connected to the articulatedsection 584.

In one enablement of the second expression of the embodiment of FIGS.17-18, the working portion 514 includes first and second segments 520and 522 wherein the surface elevation features 534 are present on thesecond segment 522 and are absent from the first segment 520. In onevariation, the working portion 514 has a maximum loop-track length, andthe first and second segments 520 and 522 together have a length greaterthan ninety percent of the maximum loop-track length. In this variation,the first segment 520 has a first bending moment of inertia and thesecond segment 522 has a second bending moment of inertia, wherein thefirst bending moment of inertia is less than the second bending momentof inertia.

A third expression of the embodiment of FIGS. 17-18 is for a medicalinstrument 518 including a flexible catheter 524, a mechanized guidewiredrive assembly 530, and a medical guidewire 512. The catheter 524 has adistal end 516 and an articulated section 584 insertable into a bodylumen of a patient, wherein the articulated section 584 is adapted to becontrolled from outside the body lumen. The medical guidewire 512includes a working portion 514 which is extendable as a loop trackbeyond the distal end 516 of the catheter 524. The working portion 514includes an exterior surface 532 having external threads 536 adapted foroperable engagement with the mechanized guidewire drive assembly 530.

The arrangements, enablements, etc. of the previously described secondexpression of the embodiment of FIGS. 17-18 are equally applicable tothe third expression of the embodiment of FIGS. 17-18, wherein thesurface elevation features 534 of such second expression are theexternal threads 536 of such third expression. In one modification, theworking portion 514 includes a third segment 526 extending from thesecond segment 522 to the first segment 520, wherein the third segment526 has a length and has a varying third diameter which is substantiallyequal to the second diameter (of the second segment 522) proximate thesecond segment 522 and which is substantially equal to the firstdiameter (of the first segment 520) proximate the first segment 520.

In one enablement of the third expression of the embodiment of FIGS.17-18, the mechanized guidewire drive assembly 530 includes a motor 544disposed within the catheter 524. In one variation, a lead 562 suppliespower to the motor 544, and the motor 544 rotates a motor shaft 548which is operatively connected to a gearbox 572 which is operativelyconnectable to the medical guidewire 512. In the same or a differentenablement, the catheter 524 is an insertion tube of a flexibleendoscope.

A second embodiment of the fifth aspect of the invention is shown inFIG. 19, wherein the portion of the second segment 622 (including theexternal threads 636 thereof) of the medical guidewire 612 extendingproximal of the gearbox 672 has been omitted for clarity but would looklike the gearbox/guidewire arrangement shown in FIG. 18. The embodimentof the medical instrument 618 of FIG. 19 is identical to the embodimentof the medical instrument 518 of FIGS. 17-18 except that the motor 644of the mechanized guidewire drive assembly 630 is disposed in the handle686, instead of in the catheter 624, and except that a longer flexiblemotor shaft 648 operatively connects the motor 644 to the gearbox 672.The articulated section 684, the control input device 688, the controlcables 692, the anchor points 694, and the lead 662 supplying power tothe motor 644 also are shown in FIG. 19.

A third embodiment of the fifth aspect of the invention is shown in FIG.20, wherein the portion of the second segment 722 (including theexternal threads 736 thereof) of the medical guidewire 712 extendingproximal of the gearbox 772 has been omitted for clarity but would looklike the gearbox/guidewire arrangement shown in FIG. 18. The embodimentof the medical instrument 718 of FIG. 20 is identical to the embodimentof the medical instrument 518 of FIGS. 17-18 except that the medicalguidewire 712, when fully extended, has a free end 721 extending beyondthe distal end 716, except that the motor 744 of the mechanizedguidewire drive assembly 730 is disposed outside the handle 786 and thecatheter 724, except that a second gearbox 773 is disposed in the handle786, except that a long flexible motor shaft 648 operatively connectsthe motor 744 to the second gearbox 773, and except that a connectingshaft 796 operatively connects the second gearbox 773 to the firstgearbox 772. The articulated section 784, the control input device 788,the control cables 792, the anchor points 794, and the lead 762supplying power to the motor 744 also are shown in FIG. 20.

A first expression of the embodiment of FIG. 20 is for a medicalinstrument 718 including a flexible catheter 724 and a medical guidewire712. The catheter 724 has a distal end 716 and an articulated section784 insertable into a body lumen of a patient, wherein the articulatedsection 784 is adapted to be controlled from outside the body lumen. Themedical guidewire 712 is extendable beyond the distal end 716 of thecatheter 724. The medical guidewire 712 includes first and secondsegments 720 and 722. The first segment 720 has a first bending momentof inertia and the second segment 722 has a second bending moment ofinertia, wherein the first bending moment of inertia is less than thesecond bending moment of inertia. The first segment 720 has a free end721 which extends beyond the distal end 716 of the catheter 724 when themedical guidewire 712 is fully extended.

In the broadest application of the first expression of the embodiment ofFIG. 20, as described in the previous paragraph, the medical instrument718 many have, but does not require a mechanized guidewire driveassembly 730, and the medical guidewire 712 may have, but does notrequire, surface elevation features 734 such as external threads 736.

A second expression of the embodiment of FIG. 20 is for a medicalinstrument 718 including a flexible catheter 724, a mechanized guidewiredrive assembly 730, and a medical guidewire 712. The catheter 724 has adistal end 716 and an articulated section 784 insertable into a bodylumen of a patient, wherein the articulated section 784 is adapted to becontrolled from outside the body lumen. The medical guidewire 712 isextendable beyond the distal end 716 of the catheter 724. The medicalguidewire 712 includes an exterior surface 732 having a repetitiveseries of spaced-apart surface elevation features 734 adapted foroperable engagement with the mechanized guidewire drive assembly 730.The medical guidewire 712 has a free end 721 which extends beyond thedistal end 716 of the catheter 724 when the medical guidewire 712 isfully extended.

A third expression of the embodiment of FIG. 20 is for a medicalinstrument 718 including a flexible catheter 724, a mechanized guidewiredrive assembly 730, and a medical guidewire 712. The catheter 724 has adistal end 716 and an articulated section 784 insertable into a bodylumen of a patient, wherein the articulated section 784 is adapted to becontrolled from outside the body lumen. The medical guidewire 712 isextendable beyond the distal end 716 of the catheter 724. The medicalguidewire 712 includes an exterior surface 732 having external threads736 adapted for operable engagement with the mechanized guidewire driveassembly 730. The medical guidewire 712 has a free end 721 which extendsbeyond the distal end 716 of the catheter 724 when the medical guidewire712 is fully extended.

Medical Instrument Having a Guidewire and an Add-to Catheter

A sixth aspect of the invention is directed to a medical instrumenthaving a guidewire and an add-to catheter, a first embodiment of whichis shown in FIGS. 21-24. A first expression of the embodiment of FIGS.21-24 is for a medical instrument 818 including a flexible catheter 824and a medical guidewire 812. The catheter 824 has a distal end 816insertable into a body lumen of a patient, and the catheter 824 isadapted to slidably receive a rail-coupling portion 800 of an adjunctmedical device 801. The medical guidewire 812 includes a working portion814 which is extendable as a loop track beyond the distal end 816 of thecatheter 824. The working portion 814 has a maximum loop-track lengthand includes first and second segments 820 and 822 together having alength greater than ninety percent of the maximum loop-track length. Thefirst segment 820 has a first bending moment of inertia and the secondsegment 822 has a second bending moment of inertia. The first bendingmoment of inertia is less than the second bending moment of inertia.

In the broadest application of the first expression of the embodiment ofFIGS. 20-24, as described in the previous paragraph, the medicalinstrument 818 many have, but does not require a mechanized guidewiredrive assembly 830, and the medical guidewire 812 may have, but does notrequire, surface elevation features 834 such as external threads 836.

Examples of adjunct medical devices 801 include, without limitation, asecond medical instrument 802 such as a medical instrument not having amedical guidewire and, as shown in the alternate embodiment of FIG. 25(wherein like reference numerals refer to like components in FIGS. 24and 25), a connector 803 adapted to slidably receive a rail-couplingportion of a second medical instrument 802 such as a medical instrumentnot having a medical guidewire. Other examples are left to the artisan.In one choice of materials, the connector consists essentially ofPolytetrafluoroethylene (PTFE). In one implementation, the PTFE reducessliding friction.

In one construction of the first expression of the embodiment of FIGS.20-24, the catheter 824 includes a rail 804, wherein the rail 804 isadapted for couplingly and slidably receiving the rail-coupling portion800 of the adjunct medical device 801. In one variation, the rail 804 isa monolithic portion of the catheter 824. In one choice of materials,the catheter 824 consists essentially of polyurethane. In anothervariation, not shown, the rail is releasably attachable to the catheter.In one modification, the rail 804 is disposed on an exterior surface ofthe catheter 824. In another modification, not shown, the rail isdisposed on an interior surface of the catheter. In one design, the rail804 includes a plurality of transversely extending notches 805 (seeFIGS. 21-22 and especially the detailed laid-open view of the rail 804in FIG. 23). In one implementation, the notches 805 provide flexibility.

In one application of the first expression of the embodiment of FIGS.20-24, the catheter 824 is an insertion tube of a flexible endoscope(with the endoscope imager, working channel, etc. omitted from FIGS.21-24 for clarity), and the adjunct medical device 801 includes aworking channel 806 adapted for receiving a medical appliance 807. Inone variation, the working channel 807 is the interior of a flexibleannular tube 808 whose exterior surface is adapted to couple to, andslide along, the rail 804. In one example, the coupling engagement isprovided by a matching tongue-and-groove arrangement. In a differentapplication, not shown, the working channel is absent, and the medicalappliance itself is adapted to couple to, and slide along, the rail.Examples of medical appliances 807 include, without limitation, imagers,irrigators, cutting blades, ultrasound end effectors, wire snares, etc.In one modification, not shown, the catheter includes two or more rails.

It is noted that the catheter 824 of the first expression of theembodiment of FIGS. 21-14 can be described as an add-to catheter,allowing for a small catheter diameter, which, with the medicalguidewire 812, allows for easier of insertion into the body lumen of apatient. This is followed by adding an adjunct medical device 801 to thecatheter 824, as needed, for a particular medical procedure. Successiveadjunct medical devices can be brought to the treatment site, used asmedically desired, and withdrawn from the patient with the catheter 824acting as a guide rail for the adjunct medical devices and remaining atthe treatment site until completion of the medical procedure.

A second expression of the embodiment of FIGS. 21-24 is for a medicalinstrument 818 including a flexible catheter 824, a mechanized guidewiredrive assembly 830, and a medical guidewire 812. The catheter 824 has adistal end 816 insertable into a body lumen of a patient, and thecatheter 824 is adapted to slidably receive a rail-coupling portion 800of an adjunct medical device 801. The medical guidewire 812 includes aworking portion 814 which is extendable as a loop track beyond thedistal end 816 of the catheter 824. The working portion 814 includes anexterior surface 832 having a repetitive series of spaced-apart surfaceelevation features 834 adapted for operable engagement with themechanized guidewire drive assembly 830.

In one construction of the second expression of the embodiment of FIGS.20-24, the catheter 824 includes a rail 804, wherein the rail 804 isadapted for couplingly and slidably receiving the rail-coupling portion800 of the adjunct medical device 801. In one variation, the rail 804includes a plurality of transversely extending notches 805. In oneapplication of the first expression of the embodiment of FIGS. 20-24,the catheter 824 is an insertion tube of a flexible endoscope, and theadjunct medical device 801 includes a working channel 806 adapted forreceiving a medical appliance 807.

In one enablement of the second expression of the embodiment of FIGS.21-24, the working portion 814 includes first and second segments 820and 822 wherein the surface elevation features 834 are present on thesecond segment 822 and are absent from the first segment 820. In onevariation, the working portion 814 has a maximum loop-track length, andthe first and second segments 820 and 822 together have a length greaterthan ninety percent of the maximum loop-track length. In this variation,the first segment 820 has a first bending moment of inertia and thesecond segment 822 has a second bending moment of inertia, wherein thefirst bending moment of inertia is less than the second bending momentof inertia.

In one example of the second expression of the embodiment of FIGS.21-24, the surface elevation features 834 are external threads 836. Inone modification, the working portion 814 includes a third segment 826extending from the second segment 822 to the first segment 820, whereinthe third segment 826 has a length and has a varying third diameterwhich is substantially equal to the second diameter (of the secondsegment 822) proximate the second segment 822 and which is substantiallyequal to the first diameter (of the first segment 820) proximate thefirst segment 820.

It is noted that the constructions, applications, etc. of the firstexpression of the embodiment of FIGS. 21-24 are equally applicable tothe second expression of the embodiment of FIGS. 21-24. In oneenablement of the second expression of the embodiment of FIGS. 21-24,the mechanized guidewire drive assembly 830 includes a motor 844disposed within the catheter 824.

A second embodiment of the sixth aspect of the invention is shown inFIGS. 26-27. A first expression of the embodiment of FIGS. 26-27 is fora medical instrument 918 including a flexible catheter 924 and a medicalguidewire 912. The catheter 924 has a distal end 916 insertable into abody lumen of a patient, and the catheter 924 is adapted to slidablyreceive a rail-coupling portion 900 of an adjunct medical device 901.The medical guidewire 912 is extendable beyond the distal end 916 of thecatheter 924. The medical guidewire 912 includes first and secondsegments 920 and 922. The first segment 920 has a first bending momentof inertia and the second segment 922 has a second bending moment ofinertia, wherein the first bending moment of inertia is less than thesecond bending moment of inertia. The first segment 920 has a free end921 which extends beyond the distal end 916 of the catheter 924 when themedical guidewire 912 is fully extended.

In the broadest application of the first expression of the embodiment ofFIGS. 26-27, as described in the previous paragraph, the medicalinstrument 918 many have, but does not require a mechanized guidewiredrive assembly 930, and the medical guidewire 912 may have, but does notrequire, surface elevation features 934 such as external threads 936. Inone construction of the first expression of the embodiment of FIGS.26-27, the catheter 924 includes a rail 904 adapted for couplingly andslidably receiving the rail-coupling portion 900 of the adjunct medicaldevice 901.

A second expression of the embodiment of FIGS. 26-27 is for a medicalinstrument 918 including a flexible catheter 924, a mechanized guidewiredrive assembly 930, and a medical guidewire 912. The catheter 924 has adistal end 916, and the catheter 924 is adapted to slidably receive arail-coupling portion 900 of an adjunct medical device 901. The medicalguidewire 912 is extendable beyond the distal end 916 of the catheter924. The medical guidewire 912 includes an exterior surface 932 having arepetitive series of spaced-apart surface elevation features 934 adaptedfor operable engagement with the mechanized guidewire drive assembly930. The medical guidewire 912 has a free end 921 which extends beyondthe distal end 916 of the catheter 924 when the medical guidewire 912 isfully extended. In one construction of the second expression of theembodiment of FIGS. 26-27, the catheter 924 includes a rail 904 adaptedfor couplingly and slidably receiving the rail-coupling portion 900 ofthe adjunct medical device 901.

A third expression of the embodiment of FIGS. 26-27 is for a medicalinstrument 918 including a flexible catheter 924, a mechanized guidewiredrive assembly 930, and a medical guidewire 912. The catheter 924 has adistal end 916, and the catheter 924 is adapted to slidably receive arail-coupling portion 900 of an adjunct medical device 901. The medicalguidewire 912 is extendable beyond the distal end 916 of the catheter924. The medical guidewire 912 includes an exterior surface 932 havingexternal threads 936 adapted for operable engagement with the mechanizedguidewire drive assembly 930. The medical guidewire 912 has a free end921 which extends beyond the distal end 916 of the catheter 924 when themedical guidewire 912 is fully extended. In one construction of thethird expression of the embodiment of FIGS. 26-27, the catheter 924includes a rail 904 adapted for couplingly and slidably receiving therail-coupling portion 900 of the adjunct medical device 901.

Several benefits and advantages are obtained from one or more of theembodiments of the invention. In one application, having a loop-track ornon-loop-track guidewire including a first segment having a bendingmoment of inertia less than that of a second segment allows easierextension of the first segment in a body lumen of a patient followed byeasier extension and temporary anchoring of the second segment andeasier advancement of the medical instrument, as can be appreciated bythe artisan. In the same or a different application, having a loop-trackor non-loop-track guidewire including an exterior surface having arepetitive series of spaced-apart surface elevation features, such asexternal threads, allows operable engagement thereof with a mechanizedguidewire drive assembly for improved guidewire extension and medicalinstrument advancement, as can be appreciated by those skilled in theart. In one employment which utilizes a mechanized guidewire driveassembly, when the surface-elevation-feature engaging component of themechanized guidewire drive assembly is located proximate the distal endof the catheter (insertion tube) of a flexible endoscope, there is lesstendency for the catheter to “loop” within the colon and cause pain tothe patient during a colonoscopy.

While the present invention has been illustrated by a description ofseveral expressions, embodiments, methods, and examples, etc. thereof,it is not the intention of the applicants to restrict or limit thespirit and scope of the appended claims to such detail. Numerous othervariations, changes, and substitutions will occur to those skilled inthe art without departing from the scope of the invention. It will beunderstood that the foregoing description is provided by way of example,and that other modifications may occur to those skilled in the artwithout departing from the scope and spirit of the appended claims.

1. A guidewire structure comprising a medical guidewire including aworking portion which is extendable as a loop track beyond a distal endof a medical instrument, wherein the working portion has a maximumloop-track length and includes first and second segments together havinga length greater than ninety percent of the maximum loop-track length,wherein the first segment has a first bending moment of inertia and thesecond segment has a second bending moment of inertia, and wherein thefirst bending moment of inertia is less than the second bending momentof inertia.
 2. The guidewire structure of claim 1, wherein the firstsegment and the second segment have substantially the same materialcomposition, wherein the first segment has a substantially-constantfirst diameter, wherein the second segment has a substantially-constantsecond diameter, and wherein the first diameter is less than the seconddiameter.
 3. The guidewire structure of claim 2, wherein the workingportion includes a third segment extending from the second segment tothe first segment, and wherein the third segment has a length and has avarying third diameter which is substantially equal to the seconddiameter proximate the second segment and which is substantially equalto the first diameter proximate the first segment.
 4. The guidewirestructure of claim 1, wherein the working portion includes a lubricioussleeve surrounding the first segment.
 5. A guidewire structurecomprising a medical guidewire including a working portion which isextendable as a loop track beyond a distal end of a medical instrumenthaving a mechanized guidewire drive assembly, wherein the workingportion includes an exterior surface having a repetitive series ofspaced-apart surface elevation features adapted for operable engagementwith the mechanized guidewire drive assembly.
 6. The guidewire structureof claim 5, wherein the working portion includes first and secondsegments, and wherein the surface elevation features are present on thesecond segment and are absent from the first segment.
 7. The guidewirestructure of claim 6, wherein the working portion has a maximumloop-track length, wherein the first and second segments together have alength greater than ninety percent of the maximum loop-track length,wherein the first segment has a first bending moment of inertia and thesecond segment has a second bending moment of inertia, and wherein thefirst bending moment of inertia is less than the second bending momentof inertia.
 8. The guidewire structure of claim 5, wherein the surfaceelevation features are chosen from the group consisting of periodicthreads, periodic teeth, periodic holes, and periodic grooves.
 9. Theguidewire structure of claim 5, wherein the surface elevation featuresare external threads.
 10. The guidewire structure of claim 9, whereinthe working portion includes first and second segments, and wherein theexternal threads are present on the second segment and are absent fromthe first segment.
 11. The guidewire structure of claim 10, wherein theworking portion has a maximum loop-track length, wherein the first andsecond segments together have a length greater than ninety percent ofthe maximum loop-track length, wherein the first segment has a firstbending moment of inertia and the second segment has a second bendingmoment of inertia, and wherein the first bending moment of inertia isless than the second bending moment of inertia.
 12. The guidewirestructure of claim 11, wherein the working portion is adapted forpatient intraluminal contact.
 13. The guidewire structure of claim 12,wherein the medical instrument is a colonoscope which includes aflexible insertion tube, and wherein the distal end of the medicalinstrument is the distal end of the flexible insertion tube of thecolonoscope.
 14. The guidewire structure of claim 11, wherein theworking portion includes a lubricious sleeve surrounding only the firstsegment.
 15. The guidewire structure of claim 11, wherein the firstsegment and the second segment have substantially the same materialcomposition, wherein the first segment has a substantially-constantfirst diameter, wherein the second segment, without considering theexternal threads, has a substantially-constant second diameter, whereinthe first diameter is less than the second diameter, wherein the workingportion includes a third segment extending from the second segment tothe first segment, and wherein the third segment has a length and has avarying third diameter which is substantially equal to the seconddiameter proximate the second segment and which is substantially equalto the first diameter proximate the first segment.
 16. A method formaking the guidewire structure of claim 11, comprising the steps of: a)obtaining a monolithic core wire having a diameter; b) machining thecore wire to create a first section, a second section, and a transitionsection extending from the second section to the first section, whereinthe first and second sections each have a substantially constantdiameter, and wherein the first diameter is less than the seconddiameter; c) obtaining a helical spring; d) disposing the helical springto surround the second section; and e) metallurgically attaching thehelical spring to the second section, wherein the first sectionsubstantially defines the first segment apart from any sleeve, andwherein the second section with the metallurgically-attached helicalspring substantially defines the second segment.
 17. A method for makingthe guidewire structure of claim 11, comprising the steps of: a)obtaining a monolithic core wire; and b) machining the core wire tocreate the first segment, apart from any sleeve, and to create thesecond segment including the external threads.
 18. A guidewire structurecomprising a medical guidewire which is extendable beyond a distal endof a medical instrument, wherein the medical guidewire includes firstand second segments, wherein the first segment has a first bendingmoment of inertia and the second segment has a second bending moment ofinertia, wherein the first bending moment of inertia is less than thesecond bending moment of inertia, and wherein the first segment has afree end which extends beyond the distal end of the medical instrumentwhen the medical guidewire is fully extended.
 19. A guidewire structurecomprising a medical guidewire which is extendable beyond a distal endof a medical instrument having a mechanized guidewire drive assembly,wherein the medical guidewire includes an exterior surface having arepetitive series of spaced-apart surface elevation features adapted foroperable engagement with the mechanized guidewire drive assembly, andwherein the medical guidewire has a free end which extends beyond thedistal end of the medical instrument when the medical guidewire is fullyextended.
 20. The guidewire structure of claim 19, wherein the surfaceelevation features are external threads.